Interrupter



G. BAIN INTERRUPTER Filed Nov. 4, 1946 Srwentor 65e/qa @ma GttornegsFeb. 24, 1942.

Patented Feb. 24, 1942 IN TERRUPTER George Bain, Owensboro, Ky.,assignor to General Motors Corporation, Detroit, Mich., a corporation ofDelaware Anuman Novemberl; 1940, serial No. 364,161

4 Claims.

This invention relates te circuit interrupters and more specifically tomercury interrupters which operate automatically when connected to asource of power to make and break a circuit to provide pulsating currenttherein. This general type of mercury interrupter is one ln which thereis provided a small contact area of carbon or some similar materialhaving a higher resistance to the flow of electrical current thanmercury. This surface is.in contact with a small body of mercury, thetwo bodies being connected in series in an electrical circuit with acurrent flowing therethrough such as the type of interrupter disclosedin U. S. Patents No. 2,107,742, issued to Samuel Ruben.

In the operation of this type of interrupter the flow of current in thematerial having the higher resistance to the mercury causes an intenseheating of the mercury in contact with the surface and the mercury inthis region vaporizes causing the current to cease flowing and thereforea cessation of the generation of any further mercury vapor. The vaporthat has been formed recondenses allowing the mercury to again contactthe surface and the same cycle is reproduced. This causes a series ofmakes and breaks in the electrical circuit and the result obtainable isa pulsating direct current. In most of the devices of this type theenclosure within which the liquid mercury is contained has a space abovethe mercury into which the same may expand and when the devices are usedas a source of supply for the various accessories, say, for example, onan automobile wherelthere is a certain vibration attendant the operationthereof, there are times at which the mercury bounces or is jarred awayfrom the carbon or similar surface to cause a mechanical break inaddition to the normal thermal breaks as caused by the operation of thedevice. This, therefore, interferes with the normal regular operation ofthe device and causes the current to be suspended for an undue length oftime and to contain irregularities which are not satisfactory from aviewpoint of current supply.

It is therefore an object of my invention to provide means to preventsuch jarring away from the normal contact surfaces and to provide aninterrupter which will give an even flow of pulsating current regardlessof the mechanical vibrations to which the device is subjected.

With this and other objects in view, the embodiment of my invention willbe best understood by reference to the following specification 66 andclaims and illustrations in drawing, in which:

Figure 1 shows a vertical section through an interrupter incorporatingmy invention;

Figure 2 shows a partial vertical section through the actualinterrupting surfaces of the device; and

Figure 3 is a sectional view taken on line 3 3 of Figure 1.

Referring now more specifically to the drawing, there is shown in Figurel a long cylindrical envelope 2 which is made of glass or some othersuitable insulator. Sealed in the upper end thereof is an electrode 4which extends down into the central cavity for a substantial distance.Mounted in the lower end of the cavity and rigidly secured therein is acircular ceramic disc 6 having'a central opening B therein in which issupported a small block I0 of carbon or other suitable resistancematerial. Into the small block of carbon there is secured a secondelectrode I2 which is sealed into the end of the glass container andconnected into an input cable I4. A body of mercury i6 is housed withinthe hollow container and is of sufficient quantity to extend from theceramic disc 6 up to a substantial disthe accompanying tance on theupper electrode 4, thus completing the circuit between the electrode 4and the carbon block I0.

In the normal operation of the device which would be operated in itsvertically shown position or a position relatively close thereto, thetwo electrodes are connected to a source of power and current flows fromelectrode l2 to the car- ;y bon button I0 through the mercury to theelectrode 4. This flow of current causes a very high current density inthe carbon block i0 and considerable heating of the mercury on the uppersurface. This is of a sufficient amount to vaporize the mercury at thispoint and mercury vapor expands and pushes away the adjacent mercury toform a small bubble such as shown at I8 in Figure 2. This breaks theelectricalcircuit but the mercury vapor may recondense to again touchthe upper surface of the block Il), reforming the circuit. The cycle isimmediately repeated and a pulsating current is obtained therefrom.

One of the uses of this type of interrupter would be to supply a highvoltage from an ordinary six volt storage battery to supply variousaccessories used on cars and in mounting such a device for operationupon a car the same would be subject to road shock and vibration and inmany instances this vibration would be suillcient to cause the body ofmercury Il to jar up away from the carbon block Il and the circuit wouldthen be mechanically broken and not thermally.

This interferes with the ordinary operation of the device and Itherefore provide a long metal sleeve 20 having a central bore 22 largerthan the outer diameter of the electrode 4 so that this metal sleeve mayslide up and down freely on the center electrode. The lower surface 24of this sleeve sits upon the upper surface of the mercury I8 and thustends to hold it down upon the carbon block and in essence provides amechanical damper to prevent road shock or other vibrations frominterfering with the normal operation of the interrupter thermally. Ithas been found that the addition of this mechanical damper assistsgreatly in preventing the mercury from jumping from the surface of thelower electrode and maintains it in contact at substantially all times.

I claim:

1. In an interrupter, an insulating casing, a block of material ofhigher resistance than mercury supported in one end thereof, anelectrode connected thereto, a body of mercury' within the casing andresting upon one face of the block, a second electrode supported by thecasing extending into the mercury and means on the upper surface of themercury to maintain the latter in contact with the resistance material.

2. In an interrupier. a cylindrical casing ofinsulatingmateriaLacarbonmasssupportedin one end thereof, an electrodeconnected thereto. abodyofmercuryinthecasingadapiedwrest upon the mass,a second electrode supported by the casing extending into the mercury,and a member floating upon the upper surface of the mercury to maintainthe same in contact with the carbon man.

3.Inaninterrupter,aninsulatingcasing,a block of carbon mmmted in one endthereof, an electrode connected thereto, a body of mercury within thecasing and resting upon the carbon, a second electrode supported by thecasing extending into the mercury and a member of appreciable weightfloating on the upper surface of the mercury within the casing tomaintain the mercury in contact with the carbon.

4. In an interrupter, a cylindrical glass casing, a block of carbonsupported in one end of the casing, an electrode connected thereto, asecond electrode supported in the oppomte end oi the casing andextending through the center thereof to a position above the carbon, abody of mercury within the casing and resting upon the carbon andextending up so that the second electrode is immersed therein and aweight slidably mounted on the second electrode and seated upon theupper surface of the mercury to maintain it in contact with the carbonsurface.

GEORGE BAIN.

